Chocolate and chestnut cake

The break down of this cake that I made for my sister (for her Christmas dessert) is as follows:

Chocolate sponge
Chocolate mousse
Chantilly cream mixed with chestnut puree
Ganache
Decoration: macarons, gold leaf and chocolate fan, chocolate squares 'plaques' and chocolate 'cigarettes' (I'll post how to do these chocolate pieces soon)